The present invention relates to the inspection of cylindrical nuclear-fuel pellets, typically having a uranium oxide base, which are used in fuel rods for nuclear reactors, with a view to detecting their surface defects and assigning the pellets to different classes depending on the nature and the significance of such defects.
The method most used to date to sort the pellets consists in examining them visually and in distributing them manually between various batches, for example those constituted by correct pellets, pellets acceptable for fuel rods assigned to regions of the reactor where the neutron flux is less, and pellets to be rejected and recycled to the start of the manufacturing process.
This manual operation is laborious and slow. Operator fatigue may lead to errors after a certain time. Finally, there is a risk of contamination, in particular when the pellets are produced from reprocessed and/or plutonium-containing fuel.
Various nuclear-fuel pellet inspection devices have already been proposed. In particular, FR-A-2,638,983 describes an apparatus for handling and for external inspection of pellets allowing each pellet in turn to be brought to a location where it is rotated about its axis, so as to allow examination along successive generatrices. Such a device, the actual examination means of which are not described, does not seem to allow a high sorting rate to be achieved.